1. Technical Field
The present invention generally relates to an integrated circuit and fabricating method thereof and more particularly to an integrated circuit with a MEMS diaphragm and fabricating method thereof.
2. Description of the Related Art
Micro electromechanical system (MEMS) technique has established a whole new technical field and industry. The MEMS technique has been widely used in a variety of microelectronic devices that have electronic and mechanical properties, for example, pressure sensors, accelerators and micro-microphones.
Since the MEMS microphone has the advantages of light, small and high signal quality, it gradually becomes the mainly stream of micro microphone. Furthermore, complementary metal oxide semiconductor (CMOS) process is usually used to fabricate the MEMS for decreasing the cost and integrating the process of the MEMES and the driving circuit thereof. FIG. 1 is a schematic cross-sectional view of the conventional MEMS microphone. Referring to FIG.1, the MEMS microphone 100 includes a conductive substrate 110, an metal oxide semiconductor device 120, an interconnecting structure 130 and a MEMS diaphragm 140. The metal oxide semiconductor device 120 and the interconnecting structure 130 are formed on the conductive substrate 110, and the interconnecting structure 130 includes a plurality of wires 132, a plurality of contact vias 134 and a plurality of dielectric layers 136. The MEMS diaphragm 140 is disposed between the wires belong two adjacent layers and electrically connected to the wire 132 of under layer and the wire 132 of over layer through the contact vias 134.
Since the MEMS diaphragm 140 is stacked by a nitride 142, a metal 144 and a nitride 146, the depth of the contact vias 134 formed above the MEMS diaphragm 140 has to control exactly to prevent the nitride 146 from being over-etching. However, during the process of tiny MEMS microphone 100, it is difficult to control the depth of the contact vias 134. Thus, the prior art also provides another MEMS diaphragm stacked by metal nitride, metal and metal nitride in sequence, wherein the metal nitride can be a etching stop layer during the process of the contact via 134. Nevertheless, the MEMS diaphragm composed of metal nitride/metal/metal nitride has larger film stress, so the performance thereof is lower than the MEMS diaphragm composed of nitride/metal/nitride.